8. Sly Stallone Is Playing Richard Rider/Charlie-27/A Ravager
Sylvester Stallone is definitely in the movie, but the nature of his role is completely unknown. There have been plenty of rumours, some of which must be way off the mark. By the law of averages, though, one of them might be right.
CosmicBookNews incited a popular early rumour, sharing a theory that the movie might include the original Guardians team from the comics (which predated Star-Lord's gang). They posited that Stallone might be playing Charlie-27; a big red-skinned spacecraft pilot, an original Guardian Of The Galaxy, and a friend of Yondu.
Bloody Disgusting had a different suggestion: could Sly be playing Richard Rider, AKA Nova, the heroic spacefaring hero at the heart of the comic book version of the Nova Corps? Rumours of Stallone carrying a helmet on set seem to support this theory.
Most recently, Heroic Hollywood claimed that unnamed sources behind the scenes told them that Stallone is simply playing one of the Ravagers. But even if that's true, surely he could be a Ravager who's hiding a big superhero secret from his gang-member friends.
Barring an unprecedented info leak, it seems likely that the true nature of Stallone's role won't be revealed until the film comes out.